Childhood obesity is more than just a cause for concern. It’s a national crisis, with alarming increases in the number of young people who are overweight and at higher risk for health problems now and later in life.

One-third of U.S. children and teens—about 25 million in all—are either overweight or on the brink of becoming so, the highest number ever recorded, according to the latest National Health and Nutrition Examination Survey.

While the trend reflects an imbalance between food consumed and physical activity in America, obesity is a complex issue related to lifestyle, environment and genes. The Centers for Disease Control and Prevention lists underlying factors that include eating fewer nutritional foods, increasing portion sizes of food, eating out more often, higher consumption of sugar-sweetened drinks, an increasingly sedentary lifestyle, spending excessive time in front of a television or computer screen, and even a fear of crime, which discourages outdoor activities. Health care advocates complain that many schools have dropped or reduced their physical education programs, and some communities lack sufficient recreational facilities.

Today’s adults are heavier than ever, too, and with more children following their example, the long-term consequences can be devastating. Overweight children who carry extra weight into adulthood are at greater risk for heart disease, high blood pressure and other health problems. Type 2 diabetes, once rare in children, increasingly is being diagnosed in young people.

The good news is that the battle for our bodies can be fought effectively beginning at home, as well as at school and the community level. By making small, permanent changes, parents and caregivers can encourage children to eat right and get fit.

“Obesity is a serious condition people need help with or they’re going to have serious consequences,” says Karen Donato, program coordinator for We Can!, a national campaign launched in 2005 by the National Institutes of Health to improve nutrition and exercise habits among children ages 8 to 13.

“The more input people get from a variety of different avenues, be it church, school, after-school programs or work, (the more opportunities) we have to make a difference.”